...when we are having a good day and in a moment I can sense a change, see sadness in my wife's eyes,
Triggers are an unfortunate part of the process. They can hit straight out of blue with absolutely no warning at all. It could be something simple, a sight, the lyric of a song, a bird pooping... anything. There were times when I felt relaxed and at ease and that, in itself, could be a trigger.
One of the things that I learned here was that when a trigger hit to delve deep to figure out the source of that trigger. What was it about, what thoughts or emotions resulted, and whether or not it was an issue to resolve or if I'd already addressed it. Eventually, I learned to disarm them, one by one. If that same trigger hit, I could dismiss it because I had already resolved it, thought about it enough, and no longer felt the need to acknowledge it. It's a process.
Sometimes I would want to share it, sometimes I'd rather sit with it for a while. More often than not, especially if it was a powerful trigger, I'd write about it here, on SI. Sometimes I could resolve it quickly. Sometimes it would take a couple of days.
Bear in mind, the process of recovery is not linear.
I always ask if she wants to talk about things...
I don't know if this will help your wife. Asking if she wants to talk about it might feel like pressure to her, as it often did with me. You know, it's a "should" factor. "Should" I talk about it? Is that best for R? If I don't feel like talking, will it hurt her? Is that bad?
So, instead of putting the ball in her court, you might try simply availing yourself. "I'm here and will listen." Or something like that. It's a simple invitation, with no pressure, real or perceived, to respond.
I would much prefer she expresses her pain than not as I will typically envision much worse than we actually discuss.
That's your problem, not hers. You need to give her whatever space she needs, the freedom to engage or withdraw. I'm sure it won't be easy, but this is the grace you can return.
Our therapist has said the first year will be hard, but getting past the anniversary will be a milestone.
For me, the first year was about my recovery. It was a rough year. As that first "antiversary" approached, I felt very anxious, dreading the triggers I might encounter. Fortunately, I had a bit of forewarning from SI members on how best to get through it. Part of that was remembering that it was just another day of surviving infidelity, no worse or better than any other day. Part of it was that I had the power to give that day whatever significance I chose. Either way, my friend, it's best to temper your expectations.
It is a milestone. No doubt.
Now, for me, realizing that I had survived that first year and felt recovered, the fact that I did not feel healed or reconciled, that another year of surviving infidelity was just beginning, triggered an intense anger stage.
That anger stage caused me to detach. And I mean really back off, refusing to talk or engage at all. That lasted for a few months. I had to do it. I had to focus on MY healing. I didn't think about her, our marriage, or reconciliation. All of my energies were directed on me and finding myself again.
In many ways year two was worse than the first. This is so common that I would venture to say that it will be the same for her. I hope that I am wrong.
Remember, reconciliation is a marathon, not a sprint.